To improve transmission operation, a hydraulic system including an auxiliary electric transmission fluid pump is provided for circulating transmission fluid in transmission columns. The transmission hydraulic system circulates the transmission fluid for both lubricating and cooling the transmission. In addition, the transmission hydraulic system establishes pressure within the automatic transmission to hold the clutches. It is desired that the auxiliary electric transmission fluid pump be provided as part of a high performance auxiliary electric motor system. The auxiliary transmission pump motor will be a part of the transmission system and may normally be submerged in the transmission fluid. However, conventional electric motor systems require a resolver sensor and associated signal digitizing circuitry to sense rotor position and rotor angular velocity for operation of permanent magnet synchronous electric motor. Such circuitry entails additional costs, additional wiring connected to the motor, and diminishes the performance of the electric motor system. In addition, submerging the rotor sensing circuitry in the fluid with the electric pump motor is problematic.
Accordingly, it is desirable to provide a robust and cost effective method and apparatus for sensorless operation of a permanent magnet synchronous motor in an electric motor system suitable for an auxiliary transmission pump motor system which reduces the number of wires connected to the motor. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.